大鼠睁眼前后视皮层神经元突触后电流变化  

Changes of post synaptic currents of neurons in visual cortex after eyes opening of newborn rats

作　　者：涂娅莉[1] 刘应兵[2] 阴正勤[1] 胡志安[3] 赵妍君[2] 张莉[2] 

机构地区：[1]第三军医大学附属西南医院眼科,重庆400038 [2]四川大学华西医学院生理学教研室,成都610041 [3]第三军医大学基础医学部生理学教研室,重庆400038

出　　处：《第三军医大学学报》2002年第11期1325-1327,共3页Journal of Third Military Medical University

基　　金：国家自然科学基金资助项目 ( 39970 2 52 ;39770 2 58;30 0 70 2 54 )

摘　　要：目的　研究大鼠发育过程中视皮层神经元的突触后电流变化 ,探讨视皮层视觉依赖性突触的形成和重新分布的细胞内机制。方法　应用脑片膜片钳全细胞记录技术 ,获得 4～ 2 8dSprague Dawleg (SD)大鼠视皮层神经元的细胞内微电极记录 ,记录突触后电流 (Postsynapticcurrents ,PSCs)的变化。结果　 (1)共记 15 6个大鼠视皮层神经元 ,根据其电生理学特性可将神经元分为 3种类型 :无反应型、单突触反应型和多突触反应型。睁眼后无反应型细胞数量显著减少 ,而多突触反应型细胞数量明显增多。 (2 )在同一刺激强度和钳制电压下 ,对视皮层神经元的输入阻抗和PSCs的各项指标进行组间比较 :①输入阻抗IR :睁眼前与睁眼后组之间有显著性差异 ,3周龄与 4周龄组之间有显著性差异。②PSCs的峰值、到达峰值所需的时间、10 %～ 90 %上升时间、10 %～ 90 %下降时间、半波宽和潜伏期 :1周龄组与 2周龄、3周龄、4周龄组之间有显著性或非常显著性差异。结论　视皮层神经元在出生后发育过程中 ,其功能的成熟表现为在形觉刺激以及局部神经元网络的整合作用下 。Objective To investigate the changes of post synaptic currents (PSCs) of neurons in developing visual cortex for intracellular mechanisms of experience dependent synapse formation and redistribution. Methods Whole cell patch clamp recordings were carried out for PSCs in the visual cortex of 57 Sprague Dawley rats (4-28 d). Results A total of 156 PSCs were recorded and might be divided into 3 types, including silent synaptic response, monosynaptic response and polysynaptic response during the first developmental month. Numbers of the neurons with the silent response was significantly larger in eye unopened group than the eye opened rats ( P <0.001). However, the incidence of polysynaptic PSCs was increased after eye opening ( P <0.01). The input resistance of the neurons was significantly stronger in rats with unopened eyes than those eye opened, in rats within 3 weeks postnatally than those in the fourth week after born. During postnatal week 1, peak value, time of peak, 10%-90% rise time, 10%-90% decay time, half width and latency to onset of PSCs were significantly lower than those of postnatal week 1 to 4. Before eye opened the peak value and time of peak of PSCs in layer IV were significantly lower than those in layer Ⅱ-Ⅲ. However, after eye opened the PSCs in layer Ⅱ-Ⅲ were not different from those in layer IV. Conclusion The function of neurons in visual cortex tends to mature after birth through activity dependent synapses formation and redistribution under the integral effects of visual stimulating and local neuronal networks.

关 键 词：大鼠 视皮层 神经元 突触后电流 全细胞记录 膜片钳 

分 类 号：R322.91[医药卫生—人体解剖和组织胚胎学] R338.8[医药卫生—基础医学]